Priority-Based Flow Control

This document provides a brief description of the Priority-based Flow Control OpEN API. Priority-based Flow Control (PFC) is defined by 802.1Qbb. it is a flow-control mechanism that allows frames to be paused based on their priority. specifies enhancement of transmission selection to support allocation of bandwidth amongst traffic classes. Should a given traffic class not use all of its allocated bandwidth, ETS allows that bandwidth to be used by other traffic classes.

THE API provides the following services:

• Get the count of incompatible configurations received from peer.
  
• Get the willingness of the peer.
  
• Get the MACSEC bypass capability of the peer.
  
• Get the capability of the peer.
  
• Get the advertised PFC Priority participation mode
  
• Get the peer priority mode for a priority.
  
• Enable an interface for PFC.
  
• Set the drop mode for the priority on an interface.
  
• Determine the minimum priority that can be configured in PFC
  
• Determine the maximum priority that can be configured in PFC.
  
• Clear the PFC stats on an interface.
  
• Get the active status on the interface.
  
• Get the PFC mode for an interface.
  
• Get the drop mode for the priority on an interface.
  
• Get the operational PFC Priority participation mode for
  
• Get the link delay allowance in bits for an interface.
  
• Determine if the peer configuration is compatible.
  
• Gets the count of compatible configurations received from peer.
  
• Get the PFC Rx Priority stat on an interface.
  
• Get the number of PFC packets transmitted.
  
• Get the PFC Rx stat on an interface.
  
• Get the PFC Tx stat on an interface.
  
• Enable/Disable deadlock detect for a priority on an interface.
  
• Get the deadlock detect mode for a priority on an interface.
  
• Set the deadlock detect interval.
  
• Get the deadlock detect interval.
  
• Set the deadlock recovery action.
  
• Get the deadlock recovery action.
  
• Set the deadlock detect time for a priority.
  
• Set the deadlock recovery time for a priority.
  
• Get the deadlock detect time and recovery time for a priority.
  

Example C Application pfc_example

Initialization

In the main function, the sample application initializes the OpEN API RPC service by calling openapiClientRegister() and waits for the RPC service in switchdrvr to start. A Client Handle is returned by openapiClientRegister() which is used while invoking the OpEN APIs. The application then exercises the associated OpEN APIs and logs informational and/or error messages on the console. The example application runs to its completion and exits.

pfc_example

pfc_example.c is a sample application that exercises the APIs provided by the PFC OpEN APIs.

Sample Output

• Usage: ./pfc_ex <test#> <arg1> <arg2> ...
• Test 1: Enable(1)/Disable(0) pfc on an interface: ./pfc_ex 1 <intf> <mode>
• Test 2: Set PFC drop mode(drop - 0, noDrop - 1) for a given interface and priority: ./pfc_ex 2 <intf> <priority> <dropMode>
• Test 3: clear the PFC stats on an interface: ./pfc_ex 3 <intf>
• Test 4: Display PFC status for a given interface : ./pfc_ex 4 <intf>
• Test 5: Enable(1)/Disable(0) deadlock detect for the priority on an interface: ./pfc_ex 5 <intf> <priority> <mode>
• Test 6: Gets deadlock detect mode for an interface: ./pfc_ex 6 <intf>
• Test 7: Sets the deadlock detection interval[10ms - 0, 100ms - 1]: ./pfc_ex 7 <detect_interval>
• Test 8: Gets the deadlock detection interval: ./pfc_ex 8
• Test 9: Sets the deadlock recovery action[Transmit - 0, Drop - 1]: ./pfc_ex 9 <action>
• Test 10: Gets the deadlock recovery action: ./pfc_ex 10
• Test 11: Sets the deadlock detect time[0 - 1500]: ./pfc_ex 11 <priority> <detect_time>
• Test 12: Sets the deadlock recovery time[0 - 1500]: ./pfc_ex 12 <priority> <recovery_time>
• Test 13: Gets the deadlock detect time and recovery time for given priority: ./pfc_ex 13 <priority>

PFC CLI/API Cross Reference

CLI Command	OpEN API Reference
(config-if-dcb)# priority-flow-control mode {on | off}	openapiIfPfcModeSet()
(config-if-dcb)# priority-flow-control priority <0-7> { drop | no-drop }	openapiIfPfcPriorityModeSet() openapiPfcMinNoDropPriorityGet() openapiPfcMaxNoDropPriorityGet()
(Priv-User Mode)# clear priority-flow-control-statistics	openapiIfPfcStatsClear()
(Priv-User Mode)# show interface priority-flow-control	openapiIfPfcStatusGet() openapiIfPfcModeGet() openapiIfPfcPriorityModeGet() openapiPfcOprPriorityModeGet() openapiPfcOperLinkDelayAllowanceGet() openapiPfcPeerCfgCompatibleGet() openapiPfcPeerCompatibleCfgCountGet() openapiPfcPeerIncompatibleCfgCountGet() openapiIfPfcRxPriorityStatGet() openapiPfcTxPriorityStatGet() openapiIfPfcRxStatGet() openapiIfPfcTxStatGet()
(config-dcb)# priority-flow-control deadlock-detect-interval <10ms | 100ms>	openapiPfcDeadlockDetectIntervalSet()
(config-dcb)# priority-flow-control deadlock-detect-time priority <0-7> detect-time <0-1500> [recovery-time <0-1500>]	openapiPfcDeadlockDetectTimeSet() openapiPfcDeadlockRecoveryTimeSet()
(config-dcb)# priority-flow-control deadlock-recovery-action <drop | forward>	openapiPfcDeadlockRecoveryActionSet()
(config-if-dcb)# [no] priority-flow-control deadlock priority <0-7>	openapiIfPfcDeadlockConfigSet()
(Priv-User Mode)# show interface <slot/port> priority-flow-control deadlock	openapiIfPfcDeadlockConfigGet() openapiPfcDeadlockDetectIntervalGet() openapiPfcDeadlockRecoveryActionGet() openapiPfcDeadlockDetectTimeGet()